I had a long chat with an engineer from the Yahoo spam team about why Gmail was better, and this was his take: When Gmail started off in beta, the mail filters were amazing. They were trained with a large corpus of Google's employee mail, skewing everything to a technical subject matter and a tightly knit network of contacts.

When Gmail hit general availability, the quality of filters was not what average users expected. Things would get flagged simply because Grandma was not in the trusted circle of silicon valley.

Eventually they bought Postini, both to boost corporate email business, but also to source a spam filter that had been battle tested across large consumer mail installs.

This surprises me. I don't remember the last time a spam message made it to my inbox with Yahoo. Maybe 7 years ago?

I get 10 spam emails a day that get past Yahoo's spam filter. The common factor in all of them is that my address is not in the "To" field. Marking them all as spam for the past several months has been completely ineffective. My solution was to filter all email without my address in the "To" field into another folder.

I don't think the Yahoo spam filter works on an individual basis like the gmail filter does.